Thermoelectric generating device



E. PAILLE THERMOELECTRIYC GENERATING DEVICE Oct. 29, 1946.

Filed Feb. 28, '1944 III ZSnnentor; fZ/Gf/YE P4145,

' iatentecl Oct. 29,1946 .=-j.,

UNITED -.,ST AT E.S PATENT OFFICE THERMoELEornro GENERATINQ EugenePaille,l..os Angeles, Calif;, -assignor to General Controls 00., poration of California.

-Glendal'e,Ca1if.-, a core.

Application February 28, 1944., Serial No. 524,157

My present invention current supplied by the service lines, it issometimes desirable to provide a source of direct current for theoperation of a sensitive device such as an electromagnetic relay orpilot valve. For this purpose it has, been proposed to employ athermoelectric generating device, or thermocouple,"and to heat thehotjunction thereof by means of an electric resistance coil. In spite ofthe fact that the efficiency of translation of alternating to directcurrent infsuch a device is very low, when only a small amount of directcurrent is required a thermoelectric generator is preferred to aconventional electrical rectifier because of the smoothness, or absenceof periodic interruptions, of the current produced by the former.

It is therefore a main object of this invention to improve theefliciency of electrically-heated thermoelectric generating devices, andI accomplish this object by so arranging the electric heating elementwith respect to the hot junction of the device that the heating lossesof the element, particularly those due to radiation and convection, arereduced to a minimum.

Other objects and advantages of the invention will be found in thedescription, the drawing, and the claims; and, for full understanding ofthe invention, reference may be had to the following detaileddescription and accompanying drawing, wherein:

Figure 1 is a longitudinal sectional view of a thermoelectric generatingdevice embodying the invention; and

Figure 2 is an end elevation of the device shown in Figure 1.

The thermoelectric generating device, as shown in the drawing, comprisesa pair of tubular members H and I2 intimately joined together at one oftheir respective ends by a weld l3. The members Hl2 are ofthermoelectrically dissimilar materials, such as, for example, thewell-known alloys Chromel and Copel, and the welded junction of themembers constitutes the hot junction of the device.

Fused or welded to the members Hl2 adjacent the free ends thereof areconductors l4 and I5, respectively; the material of each conductor beingthe same as, or thermoelectrically similar to, the material of themember to which it is attached. In the process of fusing the conductorsto the members, the conductor is pref- 7 Claims. (01. 136-4) relates tothermoelectric generating devices andmore particularly to those erablyfirst so softened by the heat that the member is firmly-embeddedtherein, as is shown in-Figure'zz. To the free ends of thernembers l il5 are welded copper leads I6 .for connecting the device't'o a load l'lwhichmay be, for example, the coil of an electromagnetic relay. Thejunctions 2i and 22 of the copper leads l6 and the conductors .l4-l5constitute effectively the cold junction of the device.

If the arrangement is'such that the distance between the generatingdevice and the load is short, the copper leads may be.dispensed with andthe conductors vMI5 connected directly to the load. However, it is notusually advisable .to extend-the conductors l4-l 5 to a considerabledistance on account of the high electrical resistivity'ofmost materialshaving good-thermoelectric properties.

,Within the hollowv of the tubularmembers i |-l2, and adjacent the .hotjunction thereof,

is an electric heating element l8 which is conveniently in the form of aresistance coil having conducting leads I9 which extend through theouter ends of the members for connection to a source of electricity (notshown), such as that provided by the usual alternating current service.Closing the outer ends of the members Hl2 is a pair of sleeves 20 ofheat-insulating material such as porcelain; the sleeves extending inclose proximity to the element, l8 so as to confine the heat thereof tothe hot junction of the device, and having central passages or bores forthe conducting leads l9.

In a'practical embodiment of the invention, the members Hl2 andconductors I l-l5 were constructed of No. 14 gauge Chromel and Copelwire. The copper leads It were also of wire of the same size and hencesufllciently rigid that the device as a whole needed no support otherthan that afforded by the attachment of the leads to the terminals ofthe load device or relay. When the amount of energy expended in theheating coil l8 was 5 Watts, the amount of energy delivered to load I!(having a, resistance substantially equal to that of the device) was0.0225 watt; such energy being sufficient to operate a sensitive D. C.electromagnetic relay,

The embodiment of my invention herein shown and described is obviouslysusceptible of modification without departure from the spirit of theinvention, and I intend therefore to be limited only by the scope of theappended claims.

' I claim as my invention: I

1. A thermoelectric generating device comprising a pair of elongatedmembers of thermoelectrically dissimilar materials joined together atone of their respective ends to form a hot junction, said members beinghollow at said ends and defining a cavity within said hot junction, andan electric element in said cavity for heating said hot junction, theother of the ends of said members being so remote from said heatingelement that they "are not substantially affected by the heat thereof.

2. A tubular thermoelectric generating device formed by a pair oftubular members of thermoelectrically dissimilar materials joinedtogether at one of their respective ends'to form a hotjunction, and anelectric heating element'within said device adjacent said hot junction,the other of the ends of said members being so remote from said heatingelement that they are not substantially affected by the heat thereof.

3. A tubular thermoelectric generating device formed by a pair oftubular members of thermoelectrically dissimilar materials joinedtogether longitudinally at one of their respective ends to form a hotjunction, and an electric heating eleelectrically dissimilar materialsjoined together at one of their respective ends to form a hot junction,an electric heating element within said'device adjacent said hotjunction, and insulating means for confinin to said hot junction theheat produced by said element.

5. A tubular thermoelectric generating device formed by a pair oftubular members of thermoelectrically dissimilar materials joinedtogether longitudinallyat one of their respective ends to formed by apair of tubular members -of thermoelectrically dissimilar materialsjoined together longitudinally at one of their respective ends to form ahot junction, an electric heating element within said device at and onclosely adjacent sides of said not junction and havin conductin leadsextending through the hollow of the device, and

a pair of heat-insulating members substantially closing the oppositeends of said device, said heatinsulating members extending in closeproximity to the opposite ends of said heating element and at least oneof them providin a passage for a conducting lead of the heating element.

7. A thermoelectric generating device comprising'a pair of relativelyshort tubular members of thermcelectrically dissimilar materials joinedtogether to form a tube providing a hot junction between the members, anelectric heating elementwithin said tube at and on closely adjacentsides of said hot junction and having conducting leads extending throughthe tube, a pair of heatinsulatingmemberssubstantially closing theoppositeends of the tube and extending adjacent said heating element, atleast one of said heatins ulating members providing a passage for aconductin lead of the heating element, and a conductor branchinglaterally from each of said tubular members adjacent the free endthereof, the material of each conductor being thermoelectrically similarto that of the tubular member from which it branches. I V

EUGENE PAILLE.

